Comment by loveparade

I guess it's surprising then that both Hadoop/Hive and Spark, which were the originators of SQL for ETL, typically work on data lakes instead of RDBMSs. In fact, RDBMs support didn't come for a long time. The choice of SQL has nothing to do with RDBMs. It's because SQL is a declarative language that's easy to parse and convert into a physical query plan that can be parallelized and optimized extremely well. Why is that? Because it's not a general-purpose imperative loosely typed brittle language like Python.